Biodegradable composition for preparing table-ware, mulching film and package and method for preparing the same

ABSTRACT

The present invention relates to a biodegradable composition for the preparation of table-ware, mulching film and package, which comprises: 2-6% by weight of starch; 35-45% by weight of plant powders; 20-30% by weight of calcium carbonate; 2-7% by weight of sorbital; 7-13% by weight of polypropene; 2-5% by weight of polyethylene; 2-6% by weight of coupling agent; 1-2% by weight of defoamer; 2-5% by weight of stearic acid; 2-6% by weight of stearate; 3-6% by weight of glycerine or epoxidized soybean oil; and 60-100 ppm photosensitizer. The present invention also relates to a method for preparing the composition, which comprises: treating a plant wastes with a diluent acid, drying and pulverizing, then mixing it with starch, polypropene, and polyethylene, sorbital, defoamer, coupling agent, stearic acid, stearate, glycerine and photosensitizer homogeneously; blending the mixture obtained in a double-screw extruder at a temperature of 160-180 C to obtain the composition of the present invention.

FIELD OF THE INVENTION

[0001] The present invention relates to a biodegradable composition anda method for preparing the same, especially to a biodegradablecomposition for the preparation of tableware, drink container, mulchingfilm and package, and a method for preparing the same.

BACKGROUND OF THE INVENTION

[0002] With the development of the modem industry, especially the rapiddevelopment of the petroleum chemical engineering, a lot of syntheticresins and plastic articles with good properties and low costs have beenprovided for the industrial and agricultural production and our dailylife. The use of plastic film, foamed plastic articles (for example,package materials, etc) and plastic sheets in many fields has greatlypromoted the industrial and agricultural productions and enrichedpeople's daily life. However, the plastic wastes after use are abandonedeverywhere, such as ground, rivers, mountains, streets and parks, whichpollutes the environment seriously and produces one of the most harmfulenvironmental pollution called “white pollution” and therefore drawsextensive attentions. In recent years, more and more countries make lawsto restrict the use of plastic films and foamed plastics. At the sametime, great efforts are made to develop various kinds of degradableresins and plastic articles.

[0003] In addition, with the acceleration of the living rhythm, snackfoods are many people's favor more and more. Snack foods need a lot oftableware and drink containers. In the past, the tableware and drinkcontainers for snack foods are mainly made of foamed plastics, which areharmful to human body and the environment at high temperatures, andtherefore are prohibited to use any more. In order to solve theseproblems, people has tried to substitute paper tableware and drinkcontainers for plastic ones for snack foods. However, the papertableware and drink containers for snack foods have the disadvantages ofmore complex production procedures and higher costs. It is also tried tosolve these problems by using plastics material and modified starch toproduce the tableware and drink containers for snack foods, but thiskind of tableware and drink containers have the disadvantages of lowerbiodegradability, higher costs and possible secondary pollution.

[0004] Similarly, plastic films, foamed plastic articles (for example,package materials, etc) and plastic sheets (extruded sheet products)have the same problems as mentioned above.

OBJECTS OF THE INVENTION

[0005] One object of the present invention is to overcome thedisadvantages of the prior art and to provide a biodegradablecomposition, especially a biodegradable composition for the preparationof tableware, drink containers, mulching films and packages.

[0006] Another object of the present invention is to provide a methodfor preparing the biodegradable composition, especially a method forpreparing the biodegradable composition for the preparation oftableware, drink containers, mulching films and packages.

THE BRIEF DESCRIPTION OF THE DRAWING

[0007]FIG. 1 shows the flow chart of the method of the present inventionfor preparing the biodegradable composition for the preparation oftableware, drink containers, mulching films and packages.

SUMMARY OF THE INVENTION

[0008] According to one aspect of the invention, it provides abiodegradable composition for the preparation of tableware, drinkcontainers, mulching films and packages, which comprises:

[0009] 2-6% by weight of starch;

[0010] 35-45% by weight of plant powders;

[0011] 20-30% by weight of calcium carbonate;

[0012] 2-7% by weight of sorbital;

[0013] 7-13% by weight of polypropene;

[0014] 2-5% by weight of polyethylene;

[0015] 2-6% by weight of coupling agent;

[0016] 1-2% by weight of defoamer;

[0017] 2-5% by weight of stearic acid;

[0018] 2-6% by weight of stearate;

[0019] 3-6% by weight of glycerine; and

[0020] 60-100 ppm photosensitizer.

[0021] According to another aspect of the present invention, it providesa method for preparing the biodegradable composition for the preparationof tableware, drink containers, mulching films and packages, whichcomprises:

[0022] (1) treating one or more plant wastes selected from the groupconsisting of sugar cane residue, peanut shell, dry pine needle, ricehusk, millet bran and soybean shell in a 0.2-1.0% by weight of sulfuricacid or hydrochloric acid solution for 2-10 hours to degrease and modifyand to wash, and then drying the same to let it have a water content ofless than 10%; mixing the obtained plant wastes with starch, sorbital,polypropene, and polyethylene, and pulverizing the obtained mixture toobtain a powder with a particle size of larger than 70 mesh; mixing theobtained powder with calcium carbonate, stearic acid, stearate, couplingagent, defoamer, glycerine or epoxidized soybean oil, andphotosensitizer homogeneously;

[0023] (2) blending the mixture obtained in step(1) in a double-screwextruder at a temperature of 160-180 C to obtain the composition of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

[0024] With the increasing care for the environment, the demand forbiodegradability of plastic articles, such as tableware, drinkcontainers, mulching films and packages, is higher and higher. Thepresent invention provides a biodegradable composition for thepreparation of tableware, drink containers, mulching films and packages,which comprises:

[0025] 2-6% by weight of starch;

[0026] 35-45% by weight of plant powders;

[0027] 20-30% by weight of calcium carbonate;

[0028] 2-7% by weight of sorbital;

[0029] 7-13% by weight of polypropene;

[0030] 2-5% by weight of polyethylene;

[0031] 2-6% by weight of coupling agent;

[0032] 1-2% by weight of defoamer;

[0033] 2-5% by weight of stearic acid;

[0034] 2-6% by weight of stearate;

[0035] 3-6% by weight of glycerine or epoxidized soybean oil; and

[0036] 60-100 ppm photosensitizer.

[0037] According to the composition of the present invention, itpreferably comprises:

[0038] 3-5% by weight of starch;

[0039] 35-40% by weight of plant powders;

[0040] 20-30% by weight of calcium carbonate;

[0041] 4-6% by weight of sorbital;

[0042] 8-11% by weight of polypropene;

[0043] 3-4% by weight of polyethylene;

[0044] 3-5% by weight of coupling agent;

[0045] 1-2% by weight of defoamer;

[0046] 3-4% by weight of stearic acid;

[0047] 3-5% by weight of stearate;

[0048] 3-5% by weight of glycerine or epoxidized soybean oil; and

[0049] 60-100 ppm photosensitizer.

[0050] According to the composition of the present invention, it morepreferably comprises 3% by weight of starch; 37% by weight of plantpowders; 25% by weight of calcium carbonate; 5% by weight of sorbital;9% by weight of polypropene; 3% by weight of polyethylene; 5% by weightof coupling agent; 4% by weight of stearic acid; 4% by weight ofstearate; 1% by weight of defoamer; 4% by weight of glycerine and 60 ppmphoto sensitizer.

[0051] According to the composition of the present invention, the starchincludes corn starch, potato starch, ipomoea batatas starch, cassavastarch and their modified starch with a grain size of larger than 70mesh.

[0052] According to the composition of the present invention, the plantpowder is the powder of one or more plants in sugar cane residue, peanutshell, dry pine needle, rice husk, millet bran and soybean shell.

[0053] According to the composition of the present invention, thecalcium carbonate is light or heavy calcium carbonate with a grain sizeof larger than 70 mesh.

[0054] According to the composition of the present invention, thecoupling agent is that known by the skilled person in the art, and ispreferably silane.

[0055] According to the composition of the present invention, thephotosensitizer is that known by the skilled person in the art, and ispreferably benzophenone.

[0056] According to the composition of the present invention, thedefoamers are those known by the skilled person in the art, and ispreferably emulsified silicone oil.

[0057] According to the composition of the present invention, thestearate is ferrite stearate, magnesium stearate or calcium stearate,and is preferably ferrite stearate.

[0058] According to another aspect of the invention, there provides amethod for preparing the biodegradable composition for the preparationof table-ware, mulching film and package, which comprises:

[0059] (1) treating one or more plant wastes selected from the groupconsisting of sugar cane residue, peanut shell, dry pine needle, ricehusk, millet bran and soybean shell in a 0.2-1.0% by weight of sulfuricacid or hydrochloric acid solution for 2-10 hours to degrease and modifyand to wash, and then drying the same to let it have a water content ofless than 10%; mixing the obtained plant wastes with starch, sorbital,polypropene, and polyethylene, and pulverizing the obtained mixture toobtain a powder with a particle size of larger than 70 mesh; mixing theobtained powder with calcium carbonate, stearic acid, stearate, couplingagent, defoamer, glycerine or epoxidized soybean oil, andphotosensitizer homogeneously;

[0060] (2) blending the mixture obtained in step(1) in a double-screwextruder at a temperature of 160-180 C to obtain the composition of thepresent invention.

[0061] According to the method of the present invention, the starchincludes corn starch, potato starch, ipomoea batatas starch, cassavastarch and their modified starch with a grain size of larger than 70mesh.

[0062] According to the method of the present invention, the plantpowder is the powder of one or more plants in sugar cane residue, peanutshell, dry pine needle, rice husk, millet bran and soybean shell.

[0063] According to the method of the present invention, the calciumcarbonate is light or heavy calcium carbonate with a grain size oflarger than 70 mesh.

[0064] According to the method of the present invention, the couplingagent is that known by the skilled person in the art, and is preferablysilane.

[0065] According to the method of the present invention, thephotosensitizer is that known by the skilled person in the art, and ispreferably benzophenone.

[0066] According to the method of the present invention, the defoamersare those known by the skilled person in the art, and is preferablyemulsified silicone oil.

[0067] According to the method of the present invention, the stearate isferrite stearate, magnesium stearate or calcium stearate, and preferablyferrite stearate.

[0068] The composition of the present invention can be widely used invarious plastic articles, such as plastic film, foamed plasticarticles(for example, package materials, etc), plastic sheets, thetableware and drink containers for snack foods and so on. When it isused in different kinds of plastic articles, the dosage and theselection of other kinds of materials are known to the skilled in theart. For example, when it is used to prepare plastic films such asagricultural film or package, the plastic ingredient is usuallypolyethylene. The ratio of plastic ingredient and composition of thepresent invention can vary between 30˜70:70˜30 by weight according tothe requirement of the final product. Similarly, when it is used toprepare extruded sheets, foamed plastic articles and the tableware anddrink containers for snack foods, the plastic ingredient is usuallypolypropylene. The ratio of plastic ingredient and composition of thepresent invention can vary between 30˜70:70˜30 by weight according tothe requirement of the final product.

[0069] The composition of the present invention can excellently improvethe biodegradability of plastic articles. The final product preparedwith the composition and plastic ingredient such as polyethylene andpolypropylene, for example, plastic films such as agricultural film orpackage, extruded sheets, foamed plastic articles, and the tableware anddrink containers for snack foods, can be fully biodegraded in 4-5 monthunder the natural conditions.

[0070] The method and device to prepare the final product, which isprepared with the composition and plastic ingredient such aspolyethylene and polypropylene, are well known to the skilled in the artand not described in detail.

[0071] The present invention will be described in further detail withthe following examples, which should not be taken as the limitation ofthe invention. If it is not specified clearly, the dosages of theingredients are by weight.

EXAMPLES1

[0072]FIG. 1 shown the flow chart of the procedures for preparing thebiodegradable composition for the preparation of table-ware, drinkcontainers, mulching film and package of the present invention.

[0073] Sugar cane residue was soaked in a 0.8% by weight of sulfuricacid solution for 5 hours. The mixture was filtered to obtain aprocessed sugar cane residue, and then was dried to have a water contentof less than 10% by weight. The mixture of 37 parts by weight of theobtained sugar cane residue, 3 parts by weight of starch, 25 parts byweight of light calcium carbonate, 5 parts by weight of sorbitol, 3parts by weight of polyethylene, and 9 parts by weight of polypropenewas pulverized in a pulverizer to obtain a powder of the mixture havinga grain size of larger than 70 mesh.

[0074] The powder of the mixture as obtained above was mixed with 4parts by weight of the glycerine, 1 parts by weight of emulsified silaneoil, 5 parts by weight of silane, 4 parts by weight of stearic acid, 4parts by weight of ferrite stearate, and 60 ppm benzophenonehomogeneously to obtain a mixture of the same. The obtained mixture wasblended and extruded and pelleted in a double-screw extruder at atemperature of 170 C to obtain a concentrate of the composition of thepresent invention. The obtained concentrate was mixed with polypropeneat a weight ratio of 500:50 homogeneously, and the mixture was molded ina mould for the preparation of table-ware. After being kept at atemperature of 35 C in the mould for 2 hours, a table-ware having goodbiodegradability was obtained.

[0075] The table-ware obtained above could be fully biodegraded in 4-5month under the natural conditions.

EXAMPLES 2-5

[0076] In a similar manner as described in Example 1, the biodegradablecompositions for the preparation of table-ware, mulching film andpackage of the present invention were prepared. The contents of the rawmaterials in theses examples were listed in the following Table. Example2 Example 3 Example 4 Example 5 Starch 3 3 3 3 Sorbitol 4 4 5 4 Sugarcane residue 15  — — 13  powder Peanut shell powder 18  15  — — Powderof dry pine — 18  — — needle Millet bran powder 5 4 15 — Soybean shellpowder — — 10 10  Rice husk powder — — 13 15  Light calcium carbonate27  27  — — Heavy calcium carbonate — — 26  26  Stearic acid 3 4 3 4Ferrite stearate 4 5 4 5 Polyethylene 3 3 4 3 Polypropene 9 8 8 9Glycerine 4 — — 4 epoxidized soybean oil — 4 4 — Silane 4 4 4 3Emulsified silicon oil 1 1 1 1 benzophenone 60 ppm 60 ppm 60 ppm 60 ppm

[0077] The compositions obtained in Examples 2-5 were mixed withpolypropene or polyethylene respectively, and the obtained mixtures wereused to prepare table-ware, mulching film and package by the technologyknown by the person skilled in the art, respectively.

[0078] The table-ware, drink containers, mulching film and packageobtained above could be fully biodegraded in 4-5 month under the naturalconditions.

INDUSTRIAL APPLICABILITY

[0079] The composition of the present invention could be used to preparevarious plastic articles, for example, to prepare various table-wares,snack containers, agricultural films, packages, extruded sheets andplastic packages. These articles could be fully biodegraded in 4-5 monthunder the natural conditions. Therefore, the environment pollution bylight plastic articles could be eliminated or greatly alleviated.

1. A biodegradable composition for the preparation of table-ware, drinkcontainers, mulching film and package, comprising: 2-6% by weight ofstarch; 35-45% by weight of plant powders; 20-30% by weight of calciumcarbonate; 2-7% by weight of sorbital; 7-13% by weight of polypropene;2-5% by weight of polyethylene; 2-6% by weight of coupling agent; 1-2%by weight of defoamer; 2-5% by weight of stearic acid; 2-6% by weight ofstearate; 3-6% by weight of glycerine or epoxidized soybean oil; and60-100 ppm photosensitizer.
 2. The composition according to claim 1,comprising: 3-5% by weight of starch; 35-40% by weight of plant powders;20-30% by weight of calcium carbonate; 4-6% by weight of sorbital; 8-11%by weight of polypropene; 3-4% by weight of polyethylene; 3-5% by weightof coupling agent; 1-2% by weight of defoamer; 3-4% by weight of stearicacid; 3-5% by weight of stearate; 3-5% by weight of glycerine orepoxidized soybean oil; and 60-100 ppm photosensitizer.
 3. Thecomposition according to claim 2, comprising: 3% by weight of starch;37% by weight of plant powders; 25% by weight of calcium carbonate; 5%by weight of sorbital; 9% by weight of polypropene; 3% by weight ofpolyethylene; 5% by weight of coupling agent; 4% by weight of stearicacid; 4% by weight of stearate; 1% by weight of defoamer; 4% by weightof glycerine or epoxidized soybean oil and 60 ppm photosensitizer. 4.The composition according to claim 1, 2 or 3, wherein the starchincludes corn starch, potato starch, ipomoea batatas starch, cassavastarch and their modified starch with a grain size of larger than 70mesh.
 5. The composition according to claim 1, 2 or 3, wherein, theplant powder is the powder of one or more plants in sugar cane residue,peanut shell, dry pine needle, rice husk, millet bran and soybean shell.6. The composition according to claim 1, 2 or 3, wherein, the calciumcarbonate is light or heavy calcium carbonate with a grain size oflarger than 70 mesh.
 7. The composition according to claim 1, 2 or 3,wherein, the coupling agent is silane.
 8. The composition according toclaim 1, 2 or 3, wherein, the stearate is ferrite stearate, magnesiumstearate or calcium stearate.
 9. The composition according to claim 1, 2or 3, wherein, the stearate is ferrite stearate.
 10. The compositionaccording to claim 1, 2 or 3, wherein, the photosensitizer isbenzophenone.
 11. The composition according to claim 1, 2 or 3, wherein,the defoamer is emulsified silicone oil.
 12. A method for preparing abiodegradable composition for the preparation of table-ware, mulchingfilm and package, comprising: (1) treating one or more plant wastesselected from the group consisting of sugar cane residue, peanut shell,dry pine needle, rice husk, millet bran and soybean shell soaked in a0.2-1.0% by weight of sulfuric acid or hydrochloric acid solution for2-10 hours to degrease and modify and to wash, and then drying the sameto let it have a water content of less than 10%; mixing the obtainedplant wastes with starch, sorbital, polypropene, and polyethylene, andpulverizing the obtained mixture to obtain a powder with a particle sizeof less than 70 mesh; mixing the obtained powder with calcium carbonate,stearic acid, stearate, coupling agent, defoamer, glycerine orepoxidized soybean oil and photosensitizer homogeneously; (2) blendingthe mixture obtained in step(1) in a double-screw extruder at atemperature of 160-180 C to obtain the composition of the presentinvention.